In order to improve system reliability and reduce device thermal fatigue failure in multiload wireless power transfer (WPT) systems for electric vehicles, the implementation of the junction temperature fluctuation suppression strategy for SiC MOSFETs is necessary. However, current methods are relatively lacking, and active thermal management has not been used in WPT systems. In this article, the relationship between circuit parameters and junction temperature of SiC MOSFET is analyzed. In particular, a junction temperature fluctuation tracking suppression strategy for SiC MOSFETs is proposed, which consists of a coarse and a fine adjustment stage. As for the former, a shunt capacitor bank switching method is implemented. In order to compensate for the coarse adjustment defects in the small adjustment range and poor effect, in fine adjustment stage, a changing driving voltage method is used. Finally, a 5-kW multiload WPT system is built for verification. Experimental results show that the proposed strategy has obvious effect on the suppression of junction temperature fluctuation and keeps temperature near the target temperature. Benefiting from this, the maximum 13.9 °C junction temperature fluctuation is completely eliminated when the power fluctuations are within 36.1% of the rated power, and the heat load of each SiC MOSFET can be independently adjusted.

中文翻译：

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无线高功率传输中 SiC MOSFET 结温波动跟踪抑制策略的分析、设计和实现

为了提高电动汽车多负载无线电力传输（WPT）系统的系统可靠性并减少器件热疲劳失效，有必要对 SiC MOSFET 实施结温波动抑制策略。然而，目前的方法相对缺乏，并且在WPT系统中还没有使用主动热管理。本文分析了SiC MOSFET的电路参数与结温之间的关系。特别地，提出了一种用于 SiC MOSFET 的结温波动跟踪抑制策略，该策略由粗调和微调阶段组成。对于前者，采用并联电容器组切换方法。为弥补微调范围小、效果差的粗调缺陷，在微调阶段，使用改变驱动电压的方法。最后，构建了一个 5 kW 多负载 WPT 系统以进行验证。实验结果表明，所提出的策略对抑制结温波动有明显效果，使温度保持在目标温度附近。受益于此，当功率波动在额定功率的36.1%以内时，最大13.9°C的结温波动被完全消除，每个SiC MOSFET的热负载都可以独立调整。